6.5mm Mannlicher 1894

The Mannlicher 1894 is one of a small number of firearms designed with a blow-forward action, and also the first of these guns. It was the creation of Ferdinand Mannlicher, a brilliant and prolific Austria inventor who is also responsible for the en-bloc clip concept, very early experimental semiautomatic rifles, and a line of turnbolt and straight-pull rifles used widely throughout Europe.

The 1894 was made only in small numbers - about 100 each in 6.5mm and 7.8mm (this one is in 6.5mm). They were tested by the US military as well as other nations, but not adopted by anyone. While they were bleeding-edge new technology at the time, they were also really not better than traditional revolvers from a practical military perspective. That doesn't prevent them from being a fascinating cul-de-sac of firearms development though!